Tag Archives: Mimas

The Cassini science team has released what will be the best map of Saturn’s moon Mimas for many decades to come. A reduced resolution version is above, and was updated after the most recent fly-bys in November 2016 and February 2017.

The moon’s large, distinguishing crater, Herschel, is seen on the map at left. The map is an equidistant (simple cylindrical) projection and has a scale of 710 feet (216 meters) per pixel at the equator. The mean radius of Mimas used for projection of this map is 123.2 miles (198.2 kilometers). The resolution of the map is 16 pixels per degree.

Since Cassini is in its final orbits and will crash into Saturn in September, and no other Saturn mission is even being planned, do not expect a better map for a very long time.

Cool image time! The photo on the right was taken by Cassini on October 22, 2016 when the spacecraft was about 115,000 miles away and has a resolution of about 3,300 feet per pixel. It highlights well Mimas’ most distinctive feature, its single gigantic crater, which also makes the tiny moon of Saturn one of the more distinctive planetary bodies in the entire solar system.

Named after the icy moon’s discoverer, astronomer William Herschel, the crater stretches 86 miles (139 kilometers) wide — almost one-third of the diameter of Mimas (246 miles or 396 kilometers) itself.

Large impact craters often have peaks in their center — see Tethys’ large crater Odysseus in The Crown of Tethys. Herschel’s peak stands nearly as tall as Mount Everest on Earth.

The mystery here is how did Mimas survive such an impact. One would think that the moon would be been split apart by the collision, and that it didn’t suggests the material involved was soft enough to absorb the dynamic forces, and that the speed of the impact was slow enough to reduce those forces overall.

The uncertainty of science: Using data from Cassini scientists have found that Saturn’s weird moon Mimas might have either an underground ocean or a misshapen inner core.

Tajeddine and his team relied on pictures taken by NASA’s Cassini spacecraft, which has been exploring the Saturn system since 2004. They built a 3D model of the moon and found that it rotates with an extra wobble, like a misshapen top spinning slightly askew. Because Mimas is nearly spherical, the wobble hinted that something lumpy, or perhaps sloshy, lay beneath the surface. The scientists tested several models of the moon’s interior to see what might give rise to the observed wobble.

It could be the core is lumpy and not spherical. It could be that there is a liquid ocean under the crust that sloshes about as the moon moves through space. Or it could be that a massive impact, the one that produced Mimas’s Death Star look with its one gigantic single crater, could have caused the wobble.

At the moment the data is not sufficient to favor any of these theories. I guess we will just have to go there to find out.

“Not simply about one mission, [Genesis] is also the history of America’s quest for the moon… Zimmerman has done a masterful job of tying disparate events together into a solid account of one of America’s greatest human triumphs.”
–San Antonio Express-News